Piezoelectric vibration gyro element, method for manufacturing the same, and piezoelectric vibration gyro sensor

A method for manufacturing a piezoelectric vibration gyro element, comprising:

• forming an outer shape of a piezoelectric element piece including a pair of detecting resonant arms extending from a central supporting part to both sides, a pair of connecting arms extending from the central supporting part to both sides in a direction perpendicular to the detecting resonant arms, two pairs of driving resonant arms extending from each far end of the connecting arms to both sides in a direction perpendicular to the connecting arms, an extension part extending from each far end of the connecting arms in a direction in which each of the connecting arms extends, and a flat surface included in side surfaces of the extension part extending to both sides along a direction in which an end surface of the extension part extends and perpendicular to in a direction in which the driving resonant arms extend;
• forming an electrode film on whole surfaces of the piezoelectric element piece and applying a photoresist film on top of the electrode film;
• exposing the photoresist film to light from one main surface of the piezoelectric element piece and from the other main surface of the piezoelectric element piece;
• removing the photoresist film that is exposed to light so as to expose the electrode film and removing the exposed electrode film by wet etching for electrode separation;
• and
• forming a tapered part that obliquely intersects a flat surface of a driving resonate arm and a flat surface of the extension part, the flat surface of the driving resonate arm extending in a direction in which the driving resonate arms extend, the flat surface of the extension part extending in a direction in which the extension part and the connecting arms extend,
• the method forming first detecting electrodes each on front and back main surfaces of the detecting resonant arms and second detecting electrodes each on side surfaces of the detecting resonant arms, forming first driving electrodes each on front and back main surfaces of the driving resonant arms and second driving electrodes each on side surfaces of the driving resonant arms, removing the electrode film from the flat surface of the extension part, and providing the end surface and the extension part with a wiring pattern passing across the end surface of the extension part in a thickness direction and joining front and back main surfaces of the extension part so as to electrically couple the first driving electrodes each on the front and back main surfaces of the driving resonant arms.